The present invention concerns a removable digital device designed for radiography, e.g., for X-ray mammography. Such an imaging device is intended to be inserted in an- X-ray machine containing an X-ray source, a means of holding the organ X-rayed and a removable imaging device.
Mammography devices are known, for example, which include an X-ray source arranged on one side of the organ to be X-rayed, a supporting table transparent to X-rays, arranged on the other side of the organ to be X-rayed, an adjustable holding platform that applies the organ on the supporting table and a housing for receiving an imaging cassette containing an exposable film.
The housing is placed in the supporting table.
After an image of the organ has been taken, the cassette containing the exposed film is extracted from its housing and the film is developed.
Such devices are used, in general, to search for possible breast cancer symptoms. A first operation consists of a systematic screening which only necessitates taking one or two films. If those films reveal cancer symptoms, a more thorough diagnosis is then undertaken, requiring a greater number of films, for example, of a particular area of the organ, using the method of image representation and visualization.
If the diagnosis reveals the presence of a cancer, it may be necessary to take a biopsy. A puncture system is then placed on the X-ray machine. The puncture system generally comprises a needle for taking the specimen in an area suspected of being cancerous, for purposes of analysis, and a needle holder. The X-ray machine then serves to secure the positioning of the needle. The puncture system can also be used for placing a hook equipped with a wire intended for marking by the surgeon of a cancerous area upon an operation.
On use of a puncture system, a first film is taken for centering of the area to be punctured and then, thanks to an X-ray source tilting mechanism, one film with a +15xc2x0 angle and a second film with a xe2x88x9215xc2x0 angle are taken for the purpose of obtaining by stereotaxis the three-dimensional coordinates of a particularly significant point and then, after the needle enters the organ, at least two control films are taken to verify that the needle is in place in the area to be punctured. In practice, a total of approximately eight x-rays are taken on use of the puncture system. The development of an exposable film takes from 3 to 5 minutes per X-ray.
Throughout the time of the biopsy operation and development of the films, the organ remains absolutely immobile in relation to the X-ray machine and is kept compressed between the table and the holding platform. The patient must therefore remain for over 30 minutes in an immobile and relatively uncomfortable position.
With a view to reducing the time of immobilization of the organ, the cassettes containing exposable films can be replaced by cassettes containing digital imaging means capable of extremely rapid imaging. The biopsy operations are thus much shorter and reduce the discomfort of those examinations. Furthermore, the digital imaging cassettes make possible an improvement of quality of the diagnosis. For economic reasons, it is desirable to use digital imaging cassettes without changing the rest of the X-ray machine. The cassette must be removable, so that it can be placed either under the table upon a diagnosis or in the puncture system upon a biopsy.
A digital imaging cassette comprises a casing inside which an X-ray signal detection device is placed. That device can, for example, contain a scintillator capable of converting the incident X-radiation into luminous radiation, an optical fiber making it possible to filter most of the X-radiation having crossed the scintillator and protecting the components situated between said optical fiber and a matrix camera with charge transfer elements (CCD) forming a sensitive zone. That detection device is relatively cumbersome and fragile. Now, it is indispensable to obtain an image of the organ X-rayed as close as possible to the patient""s chest. The sensitive zone of the cassette must therefore be placed on one edge of the latter so as to come in proximity to the patient""s chest.
The disadvantage of this type of cassette, whose sensitive, fragile and cumbersome area is situated on an edge, is the risk of damage, for example, by impact on the sensitive area, upon handling of the cassette by an operator.
This invention concerns a device whose sensitive area is protected against mechanical shocks when the cassette is not in service, while making it possible to obtain an image of the organ taken as close as possible to the chest.
The removable digital X-ray imaging device in an embodiment of the invention includes X-ray detectors placed on the edge of the device upon imaging. The digital imaging device includes means for protecting the X-ray detectors by separating said detectors from the edge of the device, the latter being in rest position.